The ability of a projection display apparatus to take input images and display them enlarged on a screen has led to the extensive use for presentations. In a presentation a commentary accompanies the images projected onto the screen. Generally, multiple pages of presentation images are used. While each page of presentation images is different, usually a number of the images are interrelated, so it is necessary to cut back and forth between related presentation pages. Therefore, users want to be able to simultaneously display at least some of multiple pages of interrelated presentation images.
Also, during question and answer sessions or when a short time is needed before a new set of images can be displayed, companies like to display corporate logos, products and other such images (which will also be referred to as specific images) instead of presentation images. In the prior art, specific images were supplied to the projection display apparatus via an image source apparatus such as a computer, video player, TV receiver or the like. Thus, the problem has been that the specific image data has had to be stored beforehand in the image source apparatus connected to the projection display apparatus.
When no images are being input to the projection display apparatus the screen remains blank. In such situations, in the prior art the projection display apparatus displays a one-color screen image called a blank image. In this situation too, users have expressed a desire to display specific images. However, this has not been possible because normal images are not being input from the image source apparatus. This problem is not limited to the projection display apparatus, but is also shared by image display apparatus that display images supplied externally.